Circuit closer



Jan. 14, 1958 E. ZANTOP 2,820,118

CIRCUIT CLOSER Filed Sept. 50, 1954 I INVENTOR ERA/5 T 214mg ITTORNEYJ,

United States Patent 2,820,118 CIRCUIT CLOSER Ernst Zantop, Wettingen,Switzerland, assignor to Aktiengesellschaft Brown, Boveri & Cie, Baden,Switzerland, a joint stock company Application September 30, 1954,Serial No. 459,266

Claims priority, application Switzerland October 2, 1953 6 Claims. (Cl.200-87) This invention relates to a circuit closer and particularly to asensitive and quick-acting circuit closer for use in the protection ofcontact rectifiers against damage by excessive currents or reversecurrents.

Protective devices employed in rectifier engineering have includedshort-circuiters comprising a normally open switch spring-biased towardsclosing and latched against closing, the latch being released by anelectromagnet to permit closing of the switch to short the leads fromthe transformer feeding the main rectifier contacts, thereby resultingin actuation of the protective circuit breakers.

Objects of the present invention are to provide circuit closers whichare sensitive and quick-acting, the circuit closers being biased toclosed position by springs and latched open by mechanisms which exertbut little force in opposition to that developed by the closing springs,whereby the latching mechanism may be released by relatively lightelectromagnets. More specifically, an object is to provide a circuitcloser including a contact on a spring-tensioned rod, a roller on arolling abutment at a slight angle to a plane normal to the path ofmovement of the rod, a latch member normally retaining the roller on theabutment, and an electromagnet for actuating the latch member to permitthe roller to slip from the abutment.

These and other objects and the advantages of the invention will beapparent from the following specification when taken with theaccompanying drawing in which Figs. 1 and 2 are schematic diagrams ofcircuit closers embodying the invention.

In the drawing, the reference characters a a identify the fixed contactsof a normally open switch having a cooperating movable contact bsupported on and separated by insulation d from a slide rod 2. The rod eis guided for vertical movement by a body 1 forming a part of thestructural assembly of a contact rectifier, and the fixed contacts areconnected electrically with the conductors from the transformer feedingthe main contacts of one phase of the rectifier. In the case of a threephase rectifier, a shorting switch is provided for each phase and thesets of fixed contacts are preferably arranged in a triangle.

The slide e is of frame or yoke form at its upper end and includes across-frame or bar e' which rests upon the supporting roller gsuperposed upon abutment roller g supported on the inclined uppersurface of an extension 11 at the base of the guide body f. The lowerface of the bar e may be formed as a knife edge contacting the roller gor, as shown, it may be rounded ofii. The rollers are held against thevertical face of the guide body f by a latch member 1' which is aone-arm lever forming the armature of an electromagnet k which isnormally energized so long as the rectifier is operating correctly, forexample is energized by the rectifier output voltage.

The slide e is biased downwardly by a spring m acting upon the lowerextension n of the slide e. The spring m is preferably formed of a stackof domed spring plates which may be telescoped or, as shown, may bearranged 2,820,118 Patented Jan. 14, 1958 2 in pairs of oppositelyfacing domed members, and is supported below and clear of the fixedcontact members.

The inclination of the top surface of the extension h to a plane normalto the vertical path of movement of the slide e is about 05 to 12,whereby the horizontal component of the pressure exerted on the roller gby the vertical pull of spring m is relatively small and may be readilyovercome by the armature i and electromagnet k. A larger angle ofinclination would of course require a heavier electromagnet to retainthe switch in open position.

Upon de-energization of the electromagnet, the armature i swings away topermit the rollers to drop from the extension h, and the switch closeswhen the rod e is pulled down by the spring m to engage the bridgecontact b with the fixed contacts a, and 11,. The abutment roller grolls downwardly and outwardly along the slightly inclined surface ofthe fixed extension h. The supporting roller g supporting the bar 2'then has in effect an abutment consisting of a downwardly and outwardlyabutment roller g and will roll to the right with a rotation opposite tothat of the abutment roller g Thus the roller detent means will providean extremely quick-acting release with small friction components uponde-energization of the electromagnet.

As shown in Fig. 2, the fixed extension h is replaced by an abutmentroller r upon which supporting roller 3 is normally retained by a latchi which is urged towards the guide body f by an adjustable spring s. Theshaft r of abutment roller r is of course mounted in the guide bodyoutside of the path of movement of the slide e. In this embodiment, theelectromagnet k is normally deenergized and must be energized by someappropriate control circuit to overcome the force of spring s when theswitch is to be closed. Upon energization, the rolling and downwardlyinclined abutment for the supporting roller g, is provided by theabutment roller r arranged for rotation about an axis offset from thelongitudinal travel of the slide rod. Thus the supporting roller g hasan effective abutment comprising the periphery of an offset rollingsurface. Since the abutment roller r is offset, an effective inclinationis obtained by the periphery of the roller. Thus this embodiment willsimilarly provide an extremely quick-acting release upon energization ofthe magnet.

I claim:

1. A circuit closer comprising a pair of normally-open fixed contacts, amovable contact adapted to bridge said fixed contacts, a slide rodconnected to said movable contact and adapted to move axially at rightangles to the plane of said fixed contacts, spring means urging said movable contact in a direction to cause engagement of the same with saidfixed contacts, a guide body guiding said slide rod during its axialmovement, and means normally latching said slide rod against switchclosing movement by said spring means; said latching means including anabutment on said guide body, said abutment having a rotary periphery, asupporting roller superposed upon said abutment, an extension on the endof said slide rod supported by said supporting roller, a latch retainingsaid roller upon said abutment, and electromagnetic means for releasingsaid latch, said roller rolling downwardly upon said rolling abutmentwith a direction of rotation opposite thereto.

2. A circuit closer as defined in claim 1, wherein said abutmentcomprises an inclined extension on said guide body, and an abutmentroller supported by said extension and supporting said supporting rollersuperposed thereon.

3. A circuit closer as defined in claim 2, wherein said inclinedextension has a downward inclination of the order of 12 to a. planenormal to the path of movement of said slide rod.

4. A a circuit closer as defined in claim 3 wherein said extension onsaids'lidc'igdlidsfhg inclined surface coop- References Cited in thefile of this patent Grating With said supporting 1131161. UNITED STATESPATENTS 5. A circuit closer as defined in claim 3 wherein said extensionon said slide rod has a k-nife-ed-ge surface coop- 1982521 Johnson 1934crating with said supporting goller. 5 2150566 Scott 1939 6. A circuitcloser a's defined in claim 1 wherein said 2543398 Bohn 1951 abutmentcomprises an abu'jt men t 01km journgllcd on FOREIGN PATENTS said guidebody offset inwardly toward the guide body from the longitudinal motionof t 'z vel of s i said abutment Follephaving a larger'diarneter thanthat 10 445 215 Germany June 2 1927 of Sald SUPPmtmg 993:669 France Nov.5, 1951

